The Portuguese has nonetheless made clear his frustration over the lack of extra summer signings, with the failure to improve in defence coming back to haunt United in last weekend's defeat at Brighton.

City are defending Premier League champions and have made another bright start to their campaign, taking seven points from three games so far.

Phelan told BBC Radio 5 Live's Sportsweek programme: "I think what is there at the moment is fierce competition within the city, and if Manchester United are at loggerheads within the club I think it just helps fuel Manchester City's cause more than anything else.

"And I think that's something they need to be very careful of because Manchester City are a very big club now and they're very well run and they know how to use certain situations, and I think that helps - unrest across the road helps."

Phelan spent five years as number two to Sir Alex Ferguson at Old Trafford, and he believes Mourinho needs to deliver the complete package of what is expected from a United manager.

Asked whether he believes Mourinho will still be in charge at the end of the season, Phelan said: "Results and performances will dictate that. The end of the season is a long, long way away.

"But he needs to now get results. He's on the back of what was a disappointing performance and result.

"It's all going to come down to a mixture of everything. Most managers are concerned with results, most clubs are concerned with results, but he has to perform as well - and the less said and the more action probably is better."